The Spawn of Rovagug look like bugs. Which is very logical and natural, since their father Rovagug looks like a bug too. Even the rust monsters who were created by Rovagug look like bugs. Even the appearances of qlippoth reminded me those of bugs. But Tarrasque the Armageddon Engine is the only exception. While it is the greatest among the Spawn, it has no trace of a bug at all. Instead it looks like... a dinosaur? To me, Tarrasque looks more like Treerazer than it looks like a bug. Which has always irritated me. I'm not sure if Tarrasque is the intellectual property of Wizard of the Coast or not (as far as I know, the name Tarrasque is from the real world mythology so Paizo can use this monster freely perhaps?), but if Paizo is so concerned about removing every last trace of Dungeons & Dragons from Pathfinder RPG, why not revise Tarrasque as well? Completely changing its appearance so that it would look more like a bug would be a good idea. Changing its name to something else would be better. I honestly have no idea why Paizo decided to make Tarrasque one of the Spawn of Rovagug in the first place (perhaps James Jacobs decided that?).
P.S. I just realized that Urtleytlar (from page 68 of From Hell's Heart), who is a Lesser Spawn of Rovagug, does not look like a bug too. Thus Tarrasque was not the only exception after all. Perhaps it was just my terrible misunderstanding, and Rovagug (and qlippoth in general) actually has nothing to do with bugs?
By the way, I have another question. Chemnosit looks like an earthworm, Kothogaz looks like a slug, Ulunat looks like a beetle, Xotani looks like a centipede. But exactly which bug do Rovagug and Volnagur resemble? I honestly have no idea.